000
FXUS63 KDLH 070306
AFDDLH
Area Forecast Discussion
National Weather Service Duluth MN
906 PM CST Tue Dec 6 2016
.UPDATE...
Issued at 906 PM CST Tue Dec 6 2016
Picked up an inch of snow here at the office with the band of snow
that moved past earlier. Seeing some pockets of cooling cloud tops
on satellite which are indicative of some bursts of moderate snow.
Have updated to account for these trends.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 247 PM CST Tue Dec 6 2016
A stacked low over the Red River Valley will gradually lift east
across northern Minnesota into northern Ontario tonight into
Wednesday. Cold air will wrap around the low as it lifts out
resulting in scattered to numerous snow showers through mid-week and
falling surface temperatures. Breezy winds today and tomorrow as the
low lifts out resulting in wind chill values below zero in some
spots.
Cyclonic flow through the next 36 hours will lead to periods of
light snow across much of the Northland. Temps aloft will actually
be fairly steady in the short term period with 850mb temps between
-10C and -12C, but at the surface temperatures will slowly fall as
this colder air mixes down through Wednesday (and even colder later
in the work week). Winds will be breezy with gusts to 30 mph or
higher possible, which may lead to reduced visibility due to blowing
snow at times. In addition to snow showers from the synoptic-scale
pattern, on the mesoscale level lake-effect snow may be possible
from the larger inland lakes which are still "open" (not frozen).
Additional snowfall amounts of 1-2 inches are expected, with the
exception of areas in north-central Minnesota from Leech Lake north
to the international border here locally higher amounts are
possible. While total accumulation over today and tomorrow may
amount to 3-5 inches in some spots, due to the long time period
during which the snow will fall no winter weather advisories are
expected.
Lows falling to the mid/upper teens tonight with wind chill values
around zero. While these temperatures may sure seem cold given the
record warm fall, these lows are actually *above* normal! (At
Duluth the average low for Dec 7 is 10.5; Forecast is 17.) Colder
Wednesday with highs in the low to mid 20s...which is actually right
around normal for Dec 7.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 247 PM CST Tue Dec 6 2016
The northland will be under a cold northwest flow for much of the
forecast period. A broad trough will be across the region that will
be left over from the strong closed low that has been keeping the
northland in clouds and snow. By Thursday the upper low will have
moved east to well over Quebec, however, there will still be a few
pieces of short wave energy that will be rotated through the nearly
northerly flow Thursday. After this shot of our first true Arctic
air of the season, there will be a moderating trend for the weekend
as the upper flow becomes more zonal, but this will be short-lived
as another surge of even much colder air will be entering the region
Monday night. If the ECMWF pans out, the 8h temperatures are
forecast into the -30C degree range.
In the meantime, we are looking at some substantial lake effect snow
beginning Wednesday night. By Wednesday night the surface low will e
well off to the east and the winds will become more northerly. In
addition, these winds will advect increasingly colder air into the
region; from the -12C range then dipping into the -17 and -18C range
by Friday. This will certainly give some delta t`s well into the -13
to -20 range, conducive for lake effect snow. In addition, there
will be a very saturated lower level of the atmosphere. And with a
prolonged snow from Wednesday night into Friday, quite a bit of snow
could accumulate.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 533 PM CST Tue Dec 6 2016
The vertically stacked low has moved into northwest Ontario with
its associated fronts rotating through Minnesota and Wisconsin.
VFR at INL at the start of the forecast and light and variable
winds due to its proximity to the low. Look for ceilings/vsbys to
drop into the MVFR range with light snow by 02Z. Gusty winds will
hold off at INL until about 17Z. Elsewhere, expect MVFR ceilings
and vsbys, with some improvement to VFR vsbys at BRD/HYR after
06Z. VFR vsbys at DLH around 17Z. Gusty winds will affect
all other terminals through the forecast.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 17 22 18 23 / 60 30 40 30
INL 19 27 18 18 / 80 80 50 30
BRD 13 19 15 19 / 40 30 40 20
HYR 16 21 18 25 / 40 30 40 40
ASX 20 25 21 27 / 30 20 50 50
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
WI...Lake Effect SnowWatch from late Wednesday night through Friday
afternoon for WIZ002>004.
MN...None.
LS...GaleWarning until 9 AM CST Wednesday for LSZ121-140>148.
&&
$$
UPDATE...GSF
SHORT TERM...JJM
LONG TERM...CLC
AVIATION...GSF